Fog generating means and techniques



June 3, 1969 H. F. POPPENDIEK FOG GENERATING MEANS AND TECHIQUES Filed July 2l, 1966 @Mmm WM @www wf@ y W if W -.;.w-...--.w u-

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United States Patent O 3,447,532 FOG GENERATING MEANS AND TECHNIQUES Heinz F. Poppendiek, La Jolla, Calif., assignor to Geoscience Ltd., a corporation of California Filed July 21, 1966, Ser. No. 567,009 Int. Cl. F243' 1/00, 3/00; A01g 13/06 US. Cl. 126-263 7 Claims ABSTRACT F THE DISCLOSURE The present invention relates to improved means and techniques for the production of a fog or mist.

iIt is often desirable in modern warfare to rapidly develop a fog for screening activities from the enemy; for example, to produce fog blankets for screening helicopters from observation by persons on the ground. The invention in its broader aspect has other uses as, for example, in the development of a mist for protection of crops against freezing.

Briefly, the apparatus and system described herein involves a stainless steel tube shaped into the form of a coil with means for applying heat to a space surrounding the coil and a source of oil under pressure which is forced through the heated spiral tube. The oil, as it liows through the tube, is heated by the heating means such that, at the exhaust end of the coil, the oil is in the form of a vapor. An important feature of this arrangement is that the heating means or heat source is external of the coil such that heat tiow is from a region surrounding the coil inwardly to the liquid or vapor within the coil. This particular positioning of the heat source with respect to the coil is important since then the oil, partially vaporized and flowing under pressure in the coil, is urged by centrifugal forces acting thereon against the outer coil wall which is in good heat transfer relation with the heat source so optimumly positioned in a region surrounding the coil.

It is, therefore, a general object of the present invention to provide means and techniques for use in a system of the characters indicated above.

A specific object of the present invention is to provide means and techniques for production of a fog or mist from lfluids normally in a liquid state as, for example, oil.

Another specific object of the present invention is to provide means and techniques whereby liquids are converted into vapor rapidly and in large quantities using apparatus which is simple, inexpensive, compact and light in weight.

Another speciiic object of the present invention is to provide apparatus for these purposes using a tube formed as a spiral with the heat source surrounding the spiral and with a liquid under pressure connected to the inlet of the spiral so as to produce a stream of vapor at the outlet end of the tube spiral rapidly and efficiently.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

FIGURE 1 illustrates apparatus in a system embodying features of the present invention;

3,447,532 Patented June 3, 1969 FIGURE 2 is a view illustrating the heat flow path to liquid being urged by centrifugal forces -against the outer wall of a spiral flow tube in accordance with features of the present invention;

FIGURE 3 illustrates a modification using a -meltable plug as a valve;

FIGURE 4 illustrates another modification that avoids the use of tubes.

Referring to the drawings, the system includes a storage tank 10 for oil, the tank 10 being in communication with a conduit 11 which extends to one end of tube 12, referred to as the oil inlet. The tube 12, as shown, extends downwardly through a container 13 and is an extension of a coil 14, the spiral or helical coil 14 being formed from the same stock as tube 12. The upper end of coil 14 is prolonged to extend radially and form the outlet 15, the outlet 15 extending out of the container 13.

The container 13, as illustrated, may be of metal lined with a heat insulating material such as a refractory cement liner 15A at its bottom, 15B at its inner cylindrical surface, and at 15C at its top or lid 13A which is tack welded at 16 to the circular wall of container 13. The spiral coil 14 is centrally held in the container 13 by a bolt 18 which extends through the lower end of container 13, through the liner 15A and through a Washer 19 that abuts the lower end of coil 13 and through a washer 20 which abuts the upper end of coil 14, a nut 21 being threaded on the upper end of bolt 18 to lirmly secure the coil within the container and more specifically between a sleeve 18A on bolt 18 and nut 21. Using this construction involving the end washers 19 and 20 and the bolt 18 which, when tightened, assures contact between adjacent convolutions of coil y14, a substantially closed air space is defined within the coil 14. This coil assembly is coated with a ceramic cement of good heat transfer properties.

The annular space between the heat insulating coating 15A, 15B, 15C and the ceramic conducting layer 22 is filled with thermite material 25 within which is embedded an igniter 26 for igniting the same; igniting wires for this purpose extend from the igniter 26 and through the outer cylindrical wall of container 13 and are connected to a source of voltage 28 through a switch 29.

In operation of the system, the igniter is energized by closing switch 29 to develop a suiciently high temperature for ignition of the thermite material 25 which, when ignited, provides a copious amount of heat for heating the external wall of each of the convolutions of the spiral 14, i.e., for producing a flow of heat radially inwardly into the spiral 14 which serves to conduct oil and/or its vapor flowing from the source of pressurized oil 10 through the then open valve 10A. It will be seen that the oil in its liquid state liows down the inlet tube 12 and then moves in a spiral path. During motion through this spiral tubular path, centrifugal forces, of course, act on the oil molecules either in the liquid or vapor state. Because of these centrifugal forces, the oil molecules, of course, are urged outwardly against the outer wall portions o'f the tube as indicated in FIGURE 2. It will be seen from this that it is necessary, in accordance with other teachings of the present invention, that the heat source produce a ilow of heat radially inwardly into the spiral 14 as also indicated in FIGURE 2.

Various modifications may be made. For example, heat sources other than thermite material may be used, i.e., in some cases an electrical heater may be used. The arrangement shown in FIGURE 1 is considered particularly useful for use by troops, particularly since the same may be made small. For example, the container 13 may be of a size comparable to a one-gallon paint can.

-Instead of requiring a manually operated valve in 10A the supply line to the spiral for preventing the llow of oil prior to use of the system, the valve may be rendered automatic in its operation, take many diierent forms arid, as shown in the modification in FIGURE 3, may incorporate a meltable plug 40 in, for example, one of the convolutions of spiral 14 such that, after the igniter 13 is energized and the thermite material develops a suicient amount of heat, the plug 40 is melted and, being under constant pressure due to the .pressurized oil source 10, is caused to ow through the remaining convolutions after the plug 40 has been heated sulliciently whereupon then the oil may ow freely to and through the spiral.

It will be appreciated also that instead of using a good heat conducting cement 22, the spiral 14 of stainless steel may ybe closely tted in good contact relationship lWithin a cylindrical copper jacket (not shown).

It will be appreciated that the helical or spiral path for the flow of oil may be formed other than by the use of tubes, For example, as shown in FIGURE 4, the spiral path for the flow of oil may be formed generally as an external screw thread on generally rectangular cross section on a rod 50 closely tted within a cylindrical copper block 52, the copper block 52 being heated by electric heater wires 54.

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modications as fall within the true spirit and scope of this invention.

I claim:

1. In an arrangement of the character described wherein it is desired to produce a mist from material which is normally a liquid, conduit means for the llow of said liquid, said conduit means dening generally a spiral path through which said liquid ows, a source of liquid connected directly to said conduit means such that a solid column of such liquid enters said spiral path, means producing a pressure which urges said liquid in its liquid -orm through said conduit means, exothermic heating means external of said spiral path and .producing a heat ow to the conduit means dening said spiral path against which said liquid in its liquid form is urged by centrifugal forces acting on the liquid as it passes through said spiral path.

2. An arrangement as set forth in claim 1 including a meltable plug which is normally effective to prevent the flow of liquid through said path but which is melted by said heat source to render said plug ineffective.

3. An arrangement as set forth in claim 1 in which said heat source is thermite material.

4. An arrangement as set forth in claim 3 including an outer casing and said thermite material is disposed between said casing and said spiral path.

5. An arrangement as set :forth in claim 4 including an igniter in heat conductive relationship to said thermite material for igniting the same.

6. An arrangement as set forth in claim 1 in which said spiral path is in the form of a spiral tube.

7. An arrangement as set forth in claim 1 in which said spiral path is dened by an external screw thread type indentation within a rod-like element, said rod-like element being closely tted within a heat conducting member.

References Cited UNITED STATES PATENTS CHARLES I. MYHRE, Prmaly Examiner.

U.S. Cl. X.R. 126-595 

